Since their discovery, printed circuit boards have become an essential part of almost every area of the electronics industry. Printed circuitry has been formed on ceramics, glazed metals and organic resin substrates for interconnecting of individual circuit components such as resistors, capacitators, inductors and semi-conductor devices. Printed circuitry has become the only economically viable technique for the interconnection of components in low as well as high volume production.
Conductive printed circuit patterns may vary from simple patterns of radially extending conductors for connecting an integrated circuit chip to a lead frame, to highly complex multilayer patterns for interconnecting a plurality of complex circuit components.
A variety of methods have been devised to produce these printed circuits and the prior art related thereto can be exemplified by such documentation as found in the form of U.S. Pat. Nos. 2,692,190, 2,721,822, 3,181,986, 3,350,498 and more recently 4,159,222, 4,440,823 and 4,465,538.
The supra enumerated and additional patent documentation on the art of developing printed circuitry clearly allows one to detect how the art has increasingly endeavored itself in essentially every phase of consumer, commercial, industrial, and military and aerospace applications to meet two conflicting demands. First, the complexity of the interconnection required, coupled with the inherent miniaturization of integrated circuits themselves have led to increased demands for further and further miniaturization of printed circuits in order to accommodate the desired integrated circuit functions within a package which is not to become so large as to lose the advantage of miniaturization in the interconnection process. Second, as circuit densities increase in response to the demand for miniaturization and the complexity and number of interconnections likewise increase, the opportunities for failures similarly increase thereby giving rise to a demand for inherently higher reliability of interconnection techniques. The response to these demands has been a series of improvements in printed circuit manufacturing processes with consequently higher densities and reliabilities being obtained.
The above should always be achieved at an affordable price to the ultimate consumer. The present invention addresses the issues of further miniaturization, reliability improvements and cost reductions of circuit boards.